ทดสอบ printf และ scanf

#include <iostream>
#include <string.h>

char * s1(char* b);

int main()
{
    setbuf(stdout, NULL);
    char *s, *b;
    s = (char *) malloc(15);
    b = (char *) malloc(15);
    strcpy(s, "test");
    strcpy(b, "xxx");
 
    s = s1(b);
 
    printf("input:");
    scanf("%15s",s);
 
    printf("%s ...",s);
     
    free(s);
    free(b);  

}

char * s1(char* b){
    return b;
}